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Space

Maps Show Mars Was Once More Like Earth 223

Posted by CmdrTaco from the also-dogs-were-once-more-like-cats dept.
vrioux writes "NASA scientists have discovered additional evidence that Mars once underwent plate tectonics, slow movement of the planet's crust, like the present-day Earth. A new map of Mars' magnetic field made by the Mars Global Surveyor spacecraft reveals a world whose history was shaped by great crustal plates being pulled apart or smashed together. ."
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Maps Show Mars Was Once More Like Earth More

Maps Show Mars Was Once More Like Earth

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  • Comment removed (Score:5, Funny)

    by account_deleted ( 4530225 ) on Tuesday October 18, 2005 @09:59AM (#13817287)
    Comment removed based on user account deletion

  • probably more common than we think (Score:5, Insightful)

    by BushCheney08 ( 917605 ) on Tuesday October 18, 2005 @10:00AM (#13817290)
    I wouldn't be surprised to find that the majority of solid planets that we examine undergo the same basic geologic mechanisms. Tectonics, subduction, spreading, etc, are probably far more common in the universe than we think.
    • The real reason? Inter-Global Warming.

    • Re:probably more common than we think (Score:5, Interesting)

      by J'raxis ( 248192 ) on Tuesday October 18, 2005 @11:15AM (#13817978) Homepage
      Tectonics might not be. One of the prevailing theories of why we have tectonic plates is that a sizeable chunk of the earth's crust got sheared off by a massive impact, leaving the remaining chunks of crust to slowly slide around the surface of the earth. The impactor that struck the earth hit at a particularly fortuitous angle; a little bit off and it would have destroyed the planet instead. Whether or not these kinds of impacts are improbable or not is still an open question -- one theory is that the impactor formed at one of the earth's Lagrange points, and it wasn't just a "random" blow from an asteroid, so it may be more common than it at first sounds.

      Incidentally, the impactor blew that crustal material clear into orbit, which ultimately coalesced into the moon. See the giant impact theory [wikipedia.org] entry on Wikipedia.

    • All solid planets already have evidence for most of these features. What has previously made the Earth unique is Plate Tectonics, a form of Global Tectonics. It allows the recycling of both the atmosphere and crustal rocks within an extended carbon cycle, which in turn produces much more complicated minerology. The Earth's surface is very young compared to most planets, both through constant erosion, and renewal from sea-floor spreading and high levels of volcanism.

      Mars is nearly or completely dead, but
    • Maybe, but the level of activity is somewhat in doubt. Earth's tectonics appear to be unusually active, thought to be a result from a collision of another planet orbitting at Earth's L4 lagrange point, shearing off much of the lighter portion of Earth's crust.

      It is known that part of the reason why Mars is now 'dead' is because the planet ceased meaningful geological activity. The same is potentially true for Venus (though its rotation rate, for whatever reason, is abysmal.
      • It has been speculated that Venus may undergo a complete crust turn over at long intervals rather than Earth's gradual spreading-center to subduction-zone process. If this is the norm among Earth sized planets that have NOT have had an early collision that stripped off much of the crust, it could be a reason for intelligent life being rare (as per the Fermi Paradox).
    • Or less common. Depends on the distribution of elements in the local region of space, I would imagine. Venus has a crust quite a bit thicker than Earth, and doesn't really have plate tectonics. Pressure just builds up until the planet melts down every hundred million years or so.

      The collision 4 billion years ago of a Mars sized body with the proto-Earth resulted in the formation of the Moon, with Earth getting more than its fair share of the metal cores and the Moon getting more than its share of the roc
  • Am I the only one for whom "click on image to start animation" seems to mean nothing?

  • Based on the site photos... (Score:5, Funny)

    by Pomme de Terre! ( 69783 ) on Tuesday October 18, 2005 @10:07AM (#13817368)
    ... it also appears to have been ruled by giant purple spiders.
    • Giant purple spiders aside, does the image show actual spots where the remnant magnetic flux is particularly strong? It seems like those spots might be an interesting place to site the first few Mars colonies.

      Since shielding from the solar wind is a big issue, a location with just a little help from the residual field (even if weak) might have some advantages over a spot with no help at all from the dead crust.

      • Re:Based on the site photos... (Score:4, Informative)

        by meringuoid ( 568297 ) on Tuesday October 18, 2005 @10:49AM (#13817749)
        Giant purple spiders aside, does the image show actual spots where the remnant magnetic flux is particularly strong? It seems like those spots might be an interesting place to site the first few Mars colonies. Since shielding from the solar wind is a big issue, a location with just a little help from the residual field (even if weak) might have some advantages over a spot with no help at all from the dead crust.

        It probably wouldn't help much. The local magnetic remnants would be tiny, not enough to significantly shield an area.

        You'd plant your colonies where there are sites of scientific interest, or resources of value to the colonists, and put up with the radiation. One thing you won't be short of on Mars is rock. Lots and lots of rock. Dig a great big tunnel into the side of Mariner Valley, end of radiation problem...

  • Journal link (Score:5, Informative)

    by brian0918 ( 638904 ) <{brian0918} {at} {gmail.com}> on Tuesday October 18, 2005 @10:11AM (#13817409)
    Here's the journal abstract:

    http://www.pnas.org/cgi/content/abstract/050746910 2v1 [pnas.org]

    "Mars currently has no global magnetic field of internal origin but must have had one in the past, when the crust acquired intense magnetization, presumably by cooling in the presence of an Earth-like magnetic field (thermoremanent magnetization). A new map of the magnetic field of Mars, compiled by using measurements acquired at an 400-km mapping altitude by the Mars Global Surveyor spacecraft, is presented here. The increased spatial resolution and sensitivity of this map provide new insight into the origin and evolution of the Mars crust. Variations in the crustal magnetic field appear in association with major faults, some previously identified in imagery and topography (Cerberus Rupes and Valles Marineris). Two parallel great faults are identified in Terra Meridiani by offset magnetic field contours. They appear similar to transform faults that occur in oceanic crust on Earth, and support the notion that the Mars crust formed during an early era of plate tectonics."
  • Does that mean the Earth will end up like Mars in the future?
    And how will this data help us terraforming Mars?

    Far from answering, I think this only leaves us with more questions asked.
    • Comment removed based on user account deletion
    • Does that mean the Earth will end up like Mars in the future?

      probably, because the evidence is looking towards unfiltered radiation being a highly destructive force on atmospheric gasses, soncider the 'ozone hole' at the poles, the one 'weak point' of the earth's own magnetosphere. while other than a rapid destuction of the ozone layer, the radiation given off by a fusion reactor the size of the sun is quite likely not something species that evolved without exposure to hard radiation can survive. roaches
      • I was going to mod this insightful, but then I decided to do some research about the facts.

        "The climate-aerosol debacle: The U.N. science advisory group, the Intergovernmental Panel on Climate Change (IPCC), has a big credibility problem. Its 1996 report, the basis for Kyoto, had to admit that the rapid warming predicted by computer models was not occurring. So they hit on an explanation to account for the discrepancy: Sulfate aerosols, particles created from the burning of coal and other sulfur-containing
    • Well yes, eventually Earth will freeze solid, or near enough so that tectonic activity no longer occurs.

      This won't happen for a very long time. The sun will scorch Earth's atmosphere away and push its orbit back during expansion first. Being closer to the sun, several times more massive, having a moon and an overall denser crust (more appropriately, a smaller fraction of lighter materials, which make up our continents) mean that Earth will take a very long time to cool so.
      • I doubt the earth will ever freeze solid. In the estimated 4BY to red giant stage for our sun, I think the planet will still have enought radioactives in the mantle to keep the interior warm. Once the sun's atmosphere expande to engulf the planet, it will heat up and start to boil away to vapor.

        Of course, the earth could get freeze if it gets knocked out of its orbit and wanders interstellar space effectively forever.

  • Mars-Earth comparison offends Martians deeply (Score:5, Funny)

    by digitaldc ( 879047 ) on Tuesday October 18, 2005 @10:21AM (#13817495)
    Martians are NOT amused by this comparison. They find it degrading, humiliating and defamatory.

    "Earthlings have never come close to inventing a Illudium PU-36 Explosive Space Modulator, nor can the 19.7 km height of Mt. Everest even touch Olympus Mons with an altitude of 27 km!", says Mars local, Marvin.

  • Liquid Cores (Score:3, Informative)

    by deathCon4 ( 917867 ) on Tuesday October 18, 2005 @10:24AM (#13817520)
    All planets (like our own) which have a dynamic liquid core have magnetic fields. The strength of the field depends on how large and dynamic the molten core of the planet remains. When planets form, they start as a liquid lava rock, and slowly cool over millions of years. As they cool, the outer crust (or mantle) solidifies, while the core remains molten. This is true of any solid planet (not gas giant) therefore any rock-type planet would most likely of had a magnetic field at one time. Mars unfortunately is far enough from the sun that it has cooled to great depth inside the planet, reducing its liquid core to a very small percent of its original size, reducing and almost eliminating its magnetic field, which is at present very weak. Another proof of this is the lack of volcanism on Mars, which by examining the topographic features was once very active.
    • The cooling of Mars's core has nothing to do with insolation. Planetary cores are molten (or not) due to the presence of radioactive elements which release heat as they decay. Mars is less dense than Earth, meaning it's core is much smaller and probably has a smaller proportion of uranium, etc than Earth. Thus, the amount of heat generated by radioactive decay dropped off much faster than here, thus ending most geological activity billions of years ago (not all of it, though, as there are indications of
      • "there are indications of volcanic activity as recent as 100 million years ago"

        Actually, there are indications of lava flows on Olympus Mons as recent as two million years ago.
      • The cooling of Mars's core has nothing to do with insolation. Planetary cores are molten (or not) due to the presence of radioactive elements which release heat as they decay. Mars is less dense than Earth, meaning it's core is much smaller and probably has a smaller proportion of uranium, etc than Earth. Thus, the amount of heat generated by radioactive decay dropped off much faster than here, thus ending most geological activity billions of years ago (not all of it, though, as there are indications of vol
    • All planets (like our own) which have a dynamic liquid core have magnetic fields.

      All of 'em, huh? You think that maybe we might be going a little bit beyond what we know? Hmm?

  • .bak (Score:2, Funny)

    by MaXiMiUS ( 923393 )
    This is a perfect example of why you should always back up your work, too bad it would take up like, 65535TB of space to back up our entire planet.

  • Mars' orbit once crossed Earth's? (Score:5, Funny)

    by Anonymous Coward on Tuesday October 18, 2005 @10:54AM (#13817795)
    I once read an interesting story about some astonomer who believed that a long time ago Mars' orbit once was highly eliptical and crossed Earth's orbit and there was a near collision. Mars used to have oceans that alternatively froze solid and melted & boiled during it's highly elliptical orbit around the Sun until a very close encounter with Earth, where the two planets' gravities caused them to do a quick dance around each other during the near-collision, slinging off most of Mars' water which then was captured by the Earth's gravity and eventually fell into our own oceans, then Mars itself got slung outward towards it's current orbit where it collided with another small planetoid, the collision resulting in the formation of the asteroid belt and Mars' current stable orbit that is vastly less eliptical that before, but still not "almost circular" like Earth's orbit..
    • That's quite a story.

      What was it from? SF, or is someone serious about that idea? Because if they are serious, I can't imagine what kind of evidence they might present for it. At least with the Big Splash notion of lunar formation they can compare Moon rocks to those from Earth...

      • I've heard a different version of this same hypothesis. I don't recall where from, it was years ago, but whoever put it forth intended it seriously, not as fiction.

        The notion that I heard was more closely related to the Big Splash you mention and less related to Mars. It held that another planetoid, not Mars, once held a highly eccentric orbit which crossed those of both Earth and Mars. It was this planetoid which collided with Earth and formed the moon, and the remnants of the broken planetoid eventually s
      • Google for "gulliver's travels mars". It will provide some interesting reading, if nothing else. Jonathan Swift described, with some degree of accuracy, the 2 moons of Mars long before anyone discovered them with telescopes. The explaination that I've heard is that the orbits of Earth and Mars used to cross, as the grand-parent poster referred to, and that humans had actually observered the 2 moons of Mars eons ago and passed the story on. Jonathan Swift supposedly heard about this and put it into his s

    • Re:Mars' orbit once crossed Earth's? (Score:4, Informative)

      by MightyMartian ( 840721 ) on Tuesday October 18, 2005 @12:49PM (#13818806) Journal
      That wasn't an astronomer, it was a quack named Velikovsky.

  • If the stripping were real it would be a great result. Instead of reading about it I'd like to see it. Can someone post a link?

  • A map! (Score:2, Informative)

    by Zinged ( 825512 )
    Don't know if this is THE map, but it is a map of Mars Crustal Magnetic Field Remnants: http://photojournal.jpl.nasa.gov/catalog/PIA02819 [nasa.gov]

  • Best evidence for water (Score:5, Interesting)

    by Council ( 514577 ) <rmunroe@gFREEBSDmail.com minus bsd> on Tuesday October 18, 2005 @11:40AM (#13818165) Homepage
    To me, the best evidence for water is this map [got.net], which they always show at NASA presentations on Mars. It's a topographic map colored by altitude, and you see that the areas below a certain depth are almost completely crater-free, contrasted strongly with the areas above that depth. This, to me, is a really, really strong argument that it was once covered in water and had a coastline.

    Looking at that map always makes an Earth-like Mars seem much more real to me.

  • ARES project (Score:3, Interesting)

    by Council ( 514577 ) <rmunroe@gFREEBSDmail.com minus bsd> on Tuesday October 18, 2005 @11:45AM (#13818208) Homepage
    When I interned at NASA/Langley Research center, I heard constantly about the ARES Project [ama-inc.com], which they're going to use to survey Mars's magnetic field in much greater detail than the global surveyor (among other things).

    And it will be the first airplane flight over another planet's surface, just 100 years after the Wright brothers first did it here.
    • Proper link here [nasa.gov].
    • What's interesting, and perhaps addressed in your link, is that flying on Mars is completely different from flying on Earth. With low gravity it may seem easier, but at only 1% of Earth's atmosphere there is not enough air viscosity for a standard airplane to fly. It cannot generate lift nor maneuver once in the air.

      X-Plane (http://www.x-plane.com/ [x-plane.com]) provides a simulated Mars flight and includes a couple of airplanes that are designed to fly on Mars, but even those planes still do not provide enough control

  • Version 1 (Score:4, Funny)

    by LaughingCoder ( 914424 ) on Tuesday October 18, 2005 @12:26PM (#13818573)
    Hmmm, maybe Mars was Earth version 1. Then the designer addressed the defects and came out with version 2.
    • Hmmm, maybe Mars was Earth version 1. Then the designer addressed the defects and came out with version 2.

      Actually, Mars was the backup planet, but after the designer position got outsourced to a job in the Eastern nebula they decided to not bother with doing nightly backups anymore.
  • Mars cooled off sooner after formation than the Earth and probably became suitable for life tens of millions of years sooner.

    Three dozen Martian meteorites have been found so far on the Earth. Probably thousands of more fell into the oceans or haven't been found yet. Drillholes in the earth find bacteria at least ten kilometers deep, so they can live in rocks long enough for an interplanetary journey. So its possible life arose first on Mars and then infected the Earth.

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